parasitic infection Flashcards
define infection
invasion by and growth of pathogenic microorganisms
define parasite and what are the 2 types?
- organism living on/in host
- dependent on host’s function so causes damage
- types: endoparasites and exoparasites
what are the 2 categories of endoparasites? examples of each
- protozoa: amoeba, cocciidia, ciliate, flagellates
- metazoa: roundworms, flatworms, flukes
describe the features of protozoa
- single celled organisms
- eukaryotic
- causes of pathogenesis varies
- no eosinophilia
describe the features of metazoa
- free living
- have intermediate hosts and vectors
- eosinophila if invade blood
what are the forms of amoebae?
- entamoeba histolytica (pathogenic in 10% cases)
- entamoeba dispar (normal commensal of GIT)
how does amoebae infection occur?
by ingestion of mature cycts in food/water/ on hands
what is the life cycle of amoebae?
- humans only reservoir
- cysts enters SI and release parasites
- invade epithelial cells and cause ulcers
- infection spreads via venous system
how do you diagnose and treat amoebae?
- wet mount (microscopy of cysts)
- treatment: nitroimidazole
state the 3 organisms and diseases caused by coccidia
- plasmodium species (malaria)
- toxoplasma (toxoplasmosis)
- crytposporidium (diarrhoea)
what are the 2 hosts of plasmodium?
human and female anopheles’ mosquito
what are the 2 stages of plasmodium in humans?
- liver
- blood
what are the symptoms of malaria?
- fever
- headache
- chills
- emesis
- myalgia
what are the complications of malaria?
- severe anaemia
- cerebral malaria
how do you diagnose malaria?
blood film
antigen detection tests
who does toxoplasmosis affect?
- mile disease in immunocompromised
- major for pregnancy
what is toxoplasmosis caused by?
- infected food
- blood transfusion
- organ transplantation
- trans-placentally to foetus
what are the symptoms of cryptosporidium?
- diarrhoea
- fever
- nausea
- emesis
- very common in HIV pt
what is the diagnosis and treatment in cryptosporidium?
- stool exam
- fluid rehydration
name a ciliate organism and the associated disease
balantidum –> balantidiasis
what are the reservoir hosts in balantidum coli?
- pigs
- rodents
- primates
what are the symptoms of balantidum coli?
- most asymptomatic
- in immunocompromised people = persistent diarrhoea, dysentery, abdo pain, weight loss, nausea
Flagellates: state organisms and associated disease
- giardia lambia –> giardiasis
- trichomonas
- leishmania (sand fly vector)
what are the symptoms of giardiasis?
diarrhoea
how is trichomonas transmitted?
sexually
what effect does trichomonas have on HIV?
- may enhance HIV risk
what are the symptoms of trichomonas?
- females: 10-50% asymptomatic (vaginal discharge, vulval itching, dysuria)
- males: 15-50% asymptomatic (discharge and dysuria)
how do you diagnose and treat trichomonas?
- microscopy
- metronidazole
describe the features of metazoan/helminths?
- multicellular
- cycles involve insect vectors and intermediate hosts
can adult worms multiply in man?
no
in what subset are helminths a burden in?
school aged children
massive effect on child development
what are the different types of worms?
- roundworms/ nematodes (ascaris, hookworm, filaria)
- flatworms/ cestodes (taenia, tapeworms)
- flukes/ trematodes (schistosoma)
what is the life cycle of ascariasis?
- live in SI and eggs are passed with faeces
- after infective eggs are swallowed, hatch and invade intestinal mucosa
- carried via portal and systemic circulation to lungs
- larvae mature in lugs and ascend and swallowed
- when reach SI, develop into adults
what are the symptoms of ascariasis?
- asymptomatic
- abdo pain
- intestinal obstruction
- adults feed on SI content = malnourishment
- penetration to lungs = Loeffler’s pneumonia
what is the diagnosis and treatment of ascariasis?
- stool exam
- albendazole, mebendazole
what is the hookworm life cycle?
- larvae carried through circulatory system to heart, then lungs
- penetrate alveoli
- ascend to be swallowed
- reach SI to mature
- in SI, attach to lumen and cause localised bleeding
what are the symptoms of hookworm?
- iron def anaemia
- cardiac complications
- local skin mainfestations
- resp symptoms
what is the diagnosis and treatment of hookworm?
- stool exam
- albendazole, mebendazole
what is the biological name of whipworm?
trichuris trichiura
what is the lifecycle of whipworm?
- eggs hatch in SI
- release larvae to mature in colon
- adults live in caecum and asc colon
- worms leave open wounds that cause inflammation of intestinal wall
what are the symptoms of whipworm?
- bloody diarrhoea
- anaemia
what is the diagnosis and treatment of whipworm?
- stool exam
- albendazole/ mebendazole
what are the 2 main types of lymphatic filariasis?
- brugia malayi
- wucheria bancrofti
what are the symptoms of these?
- causes elephantiasis when block lymphatic systems
- microfilariae are found in peripheral blood
- day = deep veins, night = peripheral circulation
how do you diagnose it?
- blood smear
- ELISA
what is loiasis?
- metazoa
- roundworms/nematodes
- causes loa loa
- can get into eye
what is the life cycle of loiasis?
- females migrate through SC tissues and may cross front of eye
- microfilariae circulate in blood
- here can be picked up by Chrysops
- in gut of fly, larvae mature into ineffective third stage larvae
- larvae infect next host when chrysops take a blood meal
what disease does tapeworm cause?
- taenia
humans only definitive host for: - taenia solium, taenia asciatica
- taenia saginta
what are the symptoms of tapeworm?
- most asymptomatic
- T. saginata often experience more symptoms = abdo pain, loss of appetite, weight loss, upset stomach
- T. solium = cysticerosis
how do you diagnose and treat tapewrom?
- tapeworm segments in stool
- identification of eggs in stool
- treatment: praziquantel
what are 3 main types of schistosomiasis?
- schistosoma mansoni: eggs to SI
- schistosoma haematobium: eggs to bladder and ureter
- schistosoma japonicum: eggs to SI
what is the life cycle of schistosomiasis?
- eggs eliminated in water
- these hatch and release miricidia (penetrates snail)
- snails release cercariae that penetrate skin
- they then migrate to different tissues
- transform into adults and females which reside in venules
- eggs move towards lumen of SI (m and j) or bladder/ureters (h)
what are the symptoms?
- days: rash/itchy skin
- months: fever, chills, cough, myalgia
- repeated infection in children can cause anaemia, malnutrition and learning difficulties
how do you diagnose and treat?
- stool/urine exam
- praziquantel
what does scabies cause?
sarcoptes scabei and live
what are the symptoms and treatment of scabies?
- rash and burrows presence
- treatment: scabicides
what are the types of lice?
- pediculus humanis corporis (body louse)
- pediculus humanis capitis (head louse)
- pthirus pubis (crab louse of pubic area)
what is the life cycle of lice?
- exist in 3 stages (eggs, nymphs, adults)
- transmission by direct contact
